This application is based on and claims the priority under 35 U.S.C. xc2xa7119 of German Patent Application 101 53 691.7, filed on Oct. 31, 2001, the entire disclosure of which is incorporated herein by reference.
The invention relates to a circular spreader apparatus including a spreader arrangement that is supported inside of tubular textile goods, such as tubular knit goods, so as to spread out or expand the tubular goods during the treatment or processing thereof.
During various processing steps or treatments of tubular textile goods, such as tubular knit goods, it is advantageous to spread out or expand the tubular goods in a circular or tubular manner. For this reason, conventionally known apparatus for treating tubular goods typically include at least one tubular expander or circular spreader that is arranged inside the tubular goods, but must be supported in some manner from outside the tubular goods. The circular spreader, from inside the tubular goods, radially outwardly spreads or expands the goods in a triangular or multi-sided polygonal or nearly round cross-sectional shape. Thus the term xe2x80x9ccircularxe2x80x9d spreader generally does not imply a true circular shape. The tubular goods are guided and supported over suitable guide elements, such as guide rollers of the internally arranged circular spreader.
As mentioned above, it is necessary to support the internally arranged circular spreader from outside of the tubular goods. This may be achieved, for example, simply by providing support roller arrangements outside of the tubular goods, so as to support the weight of and to properly position the circular spreader arranged inside the tubular goods. That of course means that the textile material of the tubular goods passes between the external support rollers and the internal circular spreader guide elements, whereby the supporting forces are transmitted through the textile fabric of the tubular goods. Disadvantageously, that can impair or deteriorate the quality of the goods, and in any event, applies additional loads to the textile fabric, which should preferably be avoided.
German Patent DE 29 35 374 and corresponding U.S. Pat. No. 4,337,630 (Strahm) disclose a known circular spreader that aims to avoid the direct mechanical support of the circular spreader by support rollers. Instead, these patents provide for the floating support of the circular spreader on a cushion of a pressurized fluid, such as a pressurized liquid or a pressurized gas, e.g. air. Particularly, the known circular spreader includes a conically tapering inlet guide part or mandrel and a conically tapering outlet guide part or mandrel at opposite ends of a central support. Furthermore, the conventional arrangement includes an inlet support structure that has a configuration matching the tapered shape of the inlet mandrel and that extends around the inlet mandrel with a guide gap therebetween, as well as an outlet support structure that has a configuration matching the tapered shape of the outlet mandrel and that extends around the outlet mandrel with a guide gap therebetween. The tubular goods are transported through the respective guide gaps between the support structures and the mandrels. The two support structures are each provided with suitable outlet openings on their respective inner circumferential surfaces facing the respective inlet and outlet mandrels, and a pressurized flow medium (a liquid or a gas) is ejected from the outlet openings toward the respective associated mandrel, so as to develop a pressurized cushion of fluid in each guide gap between each support structure and the associated mandrel. Thereby, the circular spreader is supported and held in position relative to the support structures in a contact-less manner by the pressurized fluid cushions.
Disadvantageously, the provision of a sufficient quantity of pressurized fluid at a sufficient pressure to maintain the floating support of the circular spreader, while forming and maintaining a sufficiently large tubular goods guide gap between the support structures and the mandrels, requires relatively complex, costly and problematic technical means, for example relatively powerful pressure-generating pumps or compressors, and painstaking arrangement and adjustment of the components, in order to prevent a binding surface pressure or contact between the cooperating support structures and mandrels of the circular spreader, so as to avoid damaging or deteriorating the quality of the tubular goods being processed. Furthermore, the flowing pressurized medium, e.g. a pressurized liquid or gas, ejected from the outlet openings of the support structures must penetrate directly through the textile material of the tubular goods in order to floatingly support the internally arranged mandrels of the circular spreader. This itself can disadvantageously influence the structure and the quality of the textile material of the tubular goods.
In view of the above, it is an object of the invention to further develop and improve a circular spreader of the generally known type, so as to effectively avoid a surfacial pressing or squeezing of the tubular goods in both the inlet area as well as the outlet area of the circular spreader, while supporting and positioning the circular spreader without requiring high ongoing operating costs or difficulties, and while avoiding any impairment or deterioration of the structure or quality of the textile fabric of the tubular goods. It is another object of the invention to achieve the easy adjustability of the size of the guide gaps for best accommodating different types of tubular goods. The invention further aims to avoid or overcome the disadvantages of the prior art, and to achieve additional advantages, as apparent from the present specification. The attainment of these objects is, however, not a required limitation of the claimed invention.
The above objects have been achieved according to the invention in a circular spreader for spreading tubular textile goods, comprising a central telescopable carrier or support post, a plurality of spreader arms that are radially extendable from the central carrier, struts that are carried by the spreader arms, guide elements such as guide rollers that are carried by the struts and that are adapted to guide and support the tubular goods, an inlet guide part or mandrel arranged at one end of the central carrier, an outlet guide part or mandrel arranged at the opposite end of the central carrier, an inlet support structure arranged substantially circumferentially around the inlet mandrel with an inlet guide gap therebetween, and an outlet support structure arranged substantially circumferentially around the outlet mandrel with an outlet guide gap therebetween. In this context, terms such as xe2x80x9csubstantially circumferentially aroundxe2x80x9d do not require complete circumferential encircling, but rather require only that the external support structure extends around a sufficient portion of the total perimeter of the internally arranged mandrel so as to achieve the required support thereof. However, the support structure preferably extends around almost all of the perimeter of the mandrel, leaving only two gaps through which the tubular goods can pass while transitioning from a flat configuration to a circularly expanded configuration.
Particularly according to the invention, at least one of the inlet mandrel and the outlet mandrel is magnetic, e.g. comprises one or more magnets, and the respective associated inlet support structure or outlet support structure also is magnetic, e.g. comprises one or more magnets. Preferably, the mandrel and the associated support structure both at the inlet end as well as at the outlet end are magnetic in this manner. The magnets of the mandrel and of the associated support structure are respectively magnetically polarized so as to establish a magnetic repulsion between the respective mandrel and the associated support structure so as to maintain the guide gap therebetween due to the magnetic repulsion. In other words, the magnets of the respective mandrel and the associated support structure have the same magnetic polarity oriented with respect to each other so as to establish the magnetic repulsion.
Due to the fact that the corresponding magnetic poles repel each other, an air gap is formed between the magnetic inlet mandrel and the magnetic inlet support structure, and between the magnetic outlet mandrel and the magnetic outlet support structure, due to the respective magnetic repulsion therebetween. This air gap forms the respective tubular goods guide gap, through which the tubular goods can be easily transported without hindrance and without any mechanical pressing force being applied thereto. It is also not necessary for any sort of physical or mechanical supporting substance (e.g. like air jets or liquid jets) to pass physically through the tubular goods in order to floatingly support the internally arranged circular spreader. Instead, the magnetic forces of the like-poled mutually repulsive magnets of the internal mandrels and the external support structures achieve the floating support of the circular spreader inside the tubular goods. This does not cause any impairment, deterioration, or other influence on the structure or quality of the textile material of the tubular goods. It also ensures a very low friction on the tubular goods as the tubular goods pass through the respective guide gap.
According to particular detailed embodiments of the invention, the respective mandrel and/or the respective support structure itself may overall consist of magnetic material or magnetizable material, or may be embodied as an electromagnet. Alternatively, the respective mandrel and/or the respective support structure may comprise a non-magnetic body as well as separate magnets non-integrally mounted thereon or provided therein. In any event, any one of the magnets may be embodied as a permanent magnet or as an electromagnet. For example, a particular preferred embodiment involves the inlet and outlet mandrels comprising permanent magnets, while the inlet and outlet support structures comprise electromagnets.
Especially the electromagnets are adjustable, e.g. can be variably energized, so as to vary the magnetic field strength and thus the magnetic repulsive force generated thereby. This allows the gap size of the air gap, i.e. the goods guide gap, to be easily adjusted to adapt to different types or thicknesses of the goods being treated. The permanent magnets and the electromagnets must generate a sufficiently strong magnetic field to be able to establish the largest guide gap that may be required in the foreseeable operation of the apparatus. Furthermore, in connection with such an adjustment of the inlet and/or outlet guide gap in its width, to accommodate tubular goods of differing material thicknesses, it is preferable to construct the respective inlet support structure and/or the outlet support structure from at least two approximately circle segment-shaped parts of an annular ring, which are then each individually operatively connected to suitable actuating means for moving the ring parts and thereby mechanically adjusting the gap size.
The inventive arrangement achieves a contact-less magnetic levitation or floating support of the circular spreader inside the tubular goods. Thereby especially, the guide gaps between the mandrels and the associated support structures are established and maintained in a contact-less manner. The spread-out tubular goods, such as tubular knit goods, can be transported through any required treatment process, for example using gaseous or liquid treatment media, without causing any damage or impairment of the structure or quality of the tubular goods in the area of the inlet and the outlet of the circular spreader.